IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[user]') AND TYPE in (N'U'))
BEGIN
CREATE Table [user]
(
    user_id INT IDENTITY(1,1) NOT NULL,
    user_name NVARCHAR(Max) NULL,
    password  NVARCHAR(Max) NULL,
    create_date DATETIME DEFAULT(GETDATE()),
    update_date DATETIME,
	CONSTRAINT PK_user_id PRIMARY KEY CLUSTERED (user_id)
) 
END
GO